If they lost Moria to one FB, and a goblinoid siege, they didn't deserve it in the first place.
They lost Moria to a 40d-esque "endboss" clown (unique, superpowered named clown), plus one hell of a goblin siege. The reclaim ran afoul of some nasty critter, possibly an FB, and it's worth noting that Gandalf ran into FBs/Clowns in the caverns, too... "Far, far below the deepest delving of the Dwarves, the world is gnawed by nameless things. Even Sauron knows them not. They are older than he. Now I have walked there, but I will bring no report to darken the light of day."
I have always been a little puzzled about exactly why the Balrog was the end of the line for the dwarves. Balrogs were tough, but not
that tough. There are several examples of Elves who fought Balrogs, successfully, although they pretty much always died in the end. Feanor fought several Balrogs and their troll-guard. Glorfindel killed a Balrog in single combat. Gothmog, Lord of the Balrogs himself, didn't beat Fingon until another Balrog sucker-whipped him. Ecthelion killed Gothmog. Probably some other Balrogs died in the destruction of Gondolin; pre-canon writings have the Elves suicidally swarming the Balrogs to take them out.
Granted, those were all Noldor from Valinor, who were on an entirely different level than the regular old Sindar elves like Legolas. Still, even though the Dwarves were in decline, you'd think an entire city of Dwarves could muster an effective defense against a Balrog. The Dwarves of Belegost (IIRC) were famed for being super-effective against Glaurung, the Father of Dragons, as a result of their fire-masks or whatever. And the Balrog was with the Dwarves in Moria for an entire year. You'd think they could have plotted a cave-in or something.
There are some definite parallels between their history and our noble dwarfs or should i say dwarrows or dwerrows ( tolkien's "real historical" plural form of dwarfs). How many of their mountain homes were lost because of a tantrum spiral resulting from say...melting to many masterwork metal cages?
As far as I am aware, the only dwarven settlements lost were that of the Petty-dwarves (dwarven exiles), which were hunted to death by the Sindarin Elves and probably Orcs, and repopulated very slowly; Nogrod and Belegost, which were destroyed as a side-effect of the War of Wrath, as the battles between the Host of the Valar and Morgoth destroyed most of the Blue Mountains; and Moria, which was of course lost to a Balrog until it was recolonized sometime in the Fourth Age.
Now...as for masterworks...the very last of the Elven kingdoms standing against Morgoth was Doriath. All the kingdoms of the Noldor had been destroyed, the Three Houses of the Edain (the only Men who were not in league with Morgoth) were virtually extinct. King Thingol of Doriath, a very, very ancient Elf, possibly one of the first Elves who had ever walked the Earth or at least only a generation or so removed, felt pretty secure in his fortress of Menegroth.
So one day, a man named Hurin brought Thingol the Necklace of the Dwarves out of the ruins of Doriath, one of the greatest dwarven artifacts. And Thingol looked at it and looked at the Silmaril that was then in his possession, which was essentially the greatest artifact ever made in Middle Earth, made by Feanor, the greatest Elf ever to live who set off all the events that led to The Silmarillion and the Lord of the Rings.
And Thingol thought to himself if he could combine the Necklace of the Dwarves and the Silmaril, it would be pretty awesome. The greatest thing ever. So he commissioned some Dwarves to do it.
So the Dwarves finished and it really was the Greatest Thing Ever. Thingol went to take it, the Dwarves refused to let him have it, Thingol got real uppity - along the lines of "who the heck do you think you are? I was born before your race ever existed!" and the Dwarves killed him on the spot. The Elves in Menegroth killed the Dwarves. Survivors went back to the Dwarven kingdom, and the sent out an army for revenge. The Dwarven army sacked Doriath, the Ents and some other Elves got together and retaliated and destroyed the Dwarven army.
And that's why the Dwarves and Elves in LotR don't get along. But anyway, it sounded kinda DFish to me.
Incidentaly, Galadriel (a Noldor from Valinor) met Celeborn in Doriath, and that's evidently where they both met Treebeard.
So when they say in LotR "hey Treebeard, long time no see", they
really freakin' mean it because this was all about
6500 years before the events of the Lord of the Rings.
Which is another cool thing: Moria might have been lost to a Balrog, but the Dwarves had lived in Moria for thousands of years, so all things considered, that's a pretty successful fortress.